EP1441017A1

EP1441017A1 - Transfer tape

Info

Publication number: EP1441017A1
Application number: EP02765398A
Authority: EP
Inventors: Masaru c/o GENERAL CO. LTD YAMASHITA
Original assignee: General Co Ltd; Gen Co Ltd
Current assignee: General Co Ltd; Gen Co Ltd
Priority date: 2001-10-01
Filing date: 2002-08-30
Publication date: 2004-07-28
Anticipated expiration: 2022-08-30
Also published as: GB0409798D0; EP1441017A4; GB2397784A; DE60226055T2; DE60226055D1; WO2003031530A1; JP4079617B2; GB2397784B; US7208226B2; US20040180196A1; JP2003113353A; EP1441017B1

Abstract

[An object of the present invention is] to provide transfer tape that maintains strong adhesive strength but can be reliably cut at a stipulated position. The adhesive film contains needle-shaped particles. If the adhesive strength is made high, then the adhesion between the adhesive ingredients is increased, thus forming a film that is difficult to cut. If a force is applied to the band-shaped ribbon in a direction outside the plane in which the adhesive coating is applied, then the film of the adhesive coating becomes thin and the needle-shaped particles rupture the film and cut the adhesive film. Moreover, the cut adhesive film draws the cut end to the needle-shaped particles, and as a result it is cut completely without stringiness.

Description

BACKGROUND

1. Technical Field

The present invention relates to transfer tape that maintains strong adhesive strength but can be reliably cut at a stipulated position.

2. Technical Background

A transfer tool using transfer tape that has an adhesive film formed by coating a band-shaped ribbon with an adhesive film transfers the adhesive film from the band-shaped ribbon to a targeted object, thereby adhering the targeted object to another adhering object by means of the adhesive film transferred to said targeted object. This type of transfer tool is provided with: a supply spool around which is wound the unused transfer tape, a take-up spool that takes up the band-shaped ribbon after the adhesive film is transferred, and a dispenser that is provided in an intermediate location upon the transport path between the supply spool and take-up spool and exposed to the outside.
A transfer tool of the constitution described above is used by pressing the dispenser onto the targeted object, moving the entire tool in this state, thereby transferring the adhesive film onto the targeted object and separating the transfer tool (entire tool) from the targeted object at a desired location. The adhesive film upon the band-shaped ribbon is thus cut at the dispenser onto the side on the targeted object and the side on the transfer tape.
In this operation of the transfer tool, in recent years the ease of cutting the adhesive film is considered important from the standpoint of ease of use. To wit, the adhesive film adheres the targeted object to the other adhering object so naturally it has adhesive strength. But if this adhesive strength is too high, the adhesive film cannot be easily cut when one attempts to cut it at the desired location, but rather it is stretched out in strings between the side of the targeted object and the side ofthe band-shaped ribbon (this phenomenon shall hereinafter be referred to as "stringiness").
When this stringiness occurs, in the case that the terminus of the stringiness is present on the side of the targeted object, for example, dumpling-like lumps may occur when the terminuses of the stringiness are concentrated on the targeted object, or a step may occur in the state of adhesion between the targeted object and the adhering object, or gaps may occur so that good adhesion is not achieved, On the other hand, in the same manner, in the case that the terminus of the stringiness is present on the side of the band-shaped ribbon, for example, when it is used next, the dumpling-like lumps may be transferred to the targeted object or there may be occasional cases in which the transfer of the adhesive film cannot be started from the desired position. Moreover, there is a risk of the adhesive film adhering to the dispenser itself and having deleterious effects on its operation.
To solve this problem and prevent the stringiness as described above from occurring, JP-A 2000-98233 proposes providing a plurality of protrusions on the adhesive film side of the band-shaped ribbon such that they protrude in both width directions of said band-shaped ribbon, so that these protrusions make the adhesive film partially thinner. In addition, JP-A 2001-192625 proposes a pressure-sensitive transfer type adhesive tape wherein the adhesive film is disposed upon the band-shaped ribbon in a state in which it is cut to units of a stipulated size.
However, even if these proposals suppress stringiness, the adhesive film can only be cut at the positions of the predetermined protrusions or to the units of a stipulated size, so it cannot be cut at the desired positions (of size or length). In addition, there are problems in that this increases cost due to the difficulty of manufacturing special band-shaped ribbon, and the need for facilities for coating the band-shaped ribbon with a coating cut into stipulated units.
In order to allow the adhesive film to be easily cut at the desired positions while suppressing stringiness easily and at low cost, in the past, JP-B 6-62920 proposed adhesive transfer tape wherein alginic acid is finely dispersed within an aqueous dispersal solution of the adhesive, thereby weakening the membranous character of the adhesive film and allowing it to be cut easily. In addition, JP-A 2001-240812, for example, proposes pressure-sensitive transfer adhesive tape wherein: the adhesive film contains a filler, the equation (thickness of the adhesive layer )/(filler grain size) = 0.6-8.0 is true, and the thickness of the adhesive layer is 5-200 µm.
However, in the ones containing filler proposed in the aforementioned JP-A 2001-240812, the filler is spherical so the effect of allowing the film of the adhesive film cannot be reliably obtained, so there is a problem in that the cutting effect may not be obtained depending on the film thickness, In addition, there is also a problem in that, while the amount of filler can be easily increased or the thickness of the adhesive film can be easily made thinner, the adhesive strength conversely decreases.
In addition, with the adhesive transfer tape proposed in JP-B 6-62920, the membranous character of the adhesive film is weakened so it is easily cut, its adhesive strength may be extremely reduced due to inadequate dispersion of the al ginic acid, or it may be cut at unnecessary locations, so the cutting effect cannot be reliably obtained over the entire adhesive layer.
The present invention came about in order to solve the aforementioned problems and has as its object to provide transfer tape that maintains strong adhesive strength but can be reliably cut at a stipulated position.

SUMMARY OF THE INVENTION

The present invention came about based on the following reasons.
To wit, the conventional fillers had as their object to weaken (disrupt) the viscosity among the principal components of the adhesive film (membranous character of the adhesive film), and thereby lower the overall adhesive strength and simplify its cutting. Accordingly, the conventional filler had been spherical (cutting due to the filler had not been noted), so as a result the adhesive strength had been lowered at the same time that cutting is simplified.
The present invention differs from the prior art in that it does not lower the overall adhesive strength, but rather when increasing the viscosity among the main components of the adhesive film and strengthening the overall adhesive strength, it actively improves the cutting of the film of the adhesive film. As a result, the adhesive film contains needle-shaped or preferably steeple-shaped (a shape with a sharpened end) particles,
In addition, the needle-shaped particles in this Application are defined to be preferably steeple-shaped as described above, but may also be pillar-shaped, but at this time, this means those rod-shaped (not spherical) particles wherein the ratio of the maximum grain size to the length of the particle is 1:3 or greater constitute 90% or more of all of the needle-shaped particles.
As a result, the following effect occurs. When the adhesive strength is increased, the viscosity among the adhesive components is high as described above, so a film that is not easily cut is formed. But because it contains needle-shaped particles, when a force is applied in a direction other than in the plane in which the band-shaped ribbon is coated with the adhesive film, the film of the adhesive film becomes thinner and then the needle-shaped particles rupture the film, thereby cutting the adhesive film. Then, the cut adhesive film is pulled to the needle-shaped particles in the area of the cut edge, resulting in it being cut completely without stringiness.
In passing, appropriate materials to be included in the adhesive film as the needle-shaped particles include, for example, glass, wollastonite, sepiolite, chrysotile, aluminum borate whiskers, titanium oxide whiskers and potassium titanate whiskers,
An adhesive film with its adhesive strength increased in this manner is readily transferred from the band-shaped ribbon to the targeted object and strongly adheres the targeted object to the other adhering object. Moreover, by moving the transfer tape in a direction other than in a horizontal plane with respect to the targeted object at the desired position, the needle-shaped particles rupture the film of the adhesive film and reliably cut the adhesive film.
In addition, to containing needle-shaped particles as described above the present invention also has a Mohs hardness of 6 or greater. The Mohs hardness is one scale for indicating the hardness of a substance, with 10 numbers defined from the softest mineral to the hardest which is diamond. The positions of various minerals are determined on a scale of one to 10 depending on which of the standard minerals they are first scratched by. Informally also called the scratch hardness, the Mohs hardness indicates not the absolute value of the hardness but rather the relative hardness when compared in order. The hardness of the standard minerals are diamond: 10, corundum: 9, topaz: 8, quartz: 7, feldspar: 6, apatite: 5, fluorite. 4, calcite: 3, gypsum: 2 and talc: 1.
Here, the reason why the Mohs hardness of the needle-shaped particles is set to 6 or greater is that if the Mohs hardness is softer than 6, the needle shape is readily broken at the stage of including the needle-shaped particles into the main components of the adhesive film to manufacture the final transfer tape. Moreover, by including needle-shaped particles with a Mohs hardness of 6 or greater, the film of the adhesive film can be more readily ruptured and the adhesive film can be readily cut.
In passing, materials that have a Mohs hardness of 6 or greater include, for example, glass, titanium oxide whiskers, and aluminum borate whiskers. By using them, the meritorious effects described above can be more reliably obtained without the needle shape being broken in the process of manufacturing the transfer tape.
In addition, with the constitution described above, the present invention sets the maximum grain size of the needle-shaped particles to 5-30 µm and the length of the particles to 30-500 µm. The reason for this is that, if the maximum grain size is smaller than 5 µm and the particle length is shorter than 30 µm, then the tendency not to contribute to the ease of cutting the adhesive film becomes stronger. If the maximum grain size of the needle-shaped particles is larger than 30 µm and the particle length is longer than 500 µm, then the tendency for the needle-shaped particles to become caught in the smoother of the gravure coater or the Meyer bar of the kiss coater, thereby causing streaks in the coating and deleteriously affecting the quality of coating becomes stronger.
In addition, with the constitution described above, the present invention sets the needle-shaped particle content ratio of the adhesive film composition to 1.0-3.0 wt.%. The reason for this is that, if the needle-shaped particle content is lower than 1.0%, then cases in which the ease of cutting cannot be maintained stable arise, but if higher than 3.0%, then cases in which the adhesive strength decreases may arise.
Note that the following materials may be used as the constituent ingredients of the adhesive layer other than the needle-shaped particles. The adhesive used may be acrylic-based, rubber-based or silicone-based, for example. Moreover, if necessary, a rosin-based, terpene-based or other tackifier may also be used. In addition, it is possible to use a colorant such as Phthalocyanine Blue, Phthalocyanine Green, Brilliant Carmine 6B, Permanent Yellow H10G, Lake Red, or another organic pigment which is good from the standpoint of the clarity and fastness of color. In addition, a cissing preventative agent or preservative and the like may be included.
The material used for the band-shaped ribbon may be polyethylene terephthalate, polyethylene, polypropylene, polyvinyl chloride or other plastic film, or glassine paper or the like. In addition, depending on the case, either one or both sides of the band-shaped ribbon may be treated with a mold-release agent such as a silicone resin or fluororesin.
Note that the thickness of the band-shaped ribbon is preferably 5.60 µm and particularly preferably 15-55 µm. The reason for this is that if it is thinner than 5 µm, the transfer tape is susceptible to wrinkling or kinking which may cause malfunctioning. On the other hand, if it is thicker than 60 µm, then it is difficult to include longer lengths within the limited space within the transfer tool, the materials cost increases, and it may become resistant to bending, thus causing feed or transfer malfunctions.
Moreover, the thickness to which the band-shaped ribbon is coated with the adhesive film is preferably 15-30 µm. The reason for this is that if it is thinner than 15 µm, then cases of reduced adhesive strength may occur, but it thicker than 30 µm, then cases in which the ease of cutting cannot be maintained stably may occur. Note that the band-shaped ribbon may be coated with the adhesive film using a kiss coater, gravure coater, comma coater or by other method.

BRIEF EXPLANATION OF THE DRAWINGS

FIG. 1 is a table of the conditions in the Working Examples and Comparative Examples, along with evaluations from various tests and overall evaluations.
FIG. 2 is a table of the conditions in the Working Examples, along with evaluations from various tests and overall evaluations.

DETAILED DESCRIPTION

Here follows a description of the meritorious effects of the present invention made with reference to FIG. 1 and FIG. 2. In the following, Working Examples 1-11 are modes wherein the present invention is adopted, with FIG. 1 and FIG. 2 illustrating the correspondence between the various Working Examples and the Claims. In addition, the Comparative Examples are modes wherein the present invention is not adopted. Moreover, Working Examples 1-7 and Comparative Examples 1 and 2 adopt a uniform 1.0 parts by weight as the amount of needle-shaped particles and spherical particles. The other conditions are presented in FIG. 1 and FIG. 2.
The adhesive coating used in the tests had the following composition:

Needle-shaped or spherical particles: 1.0 parts by weight (Working Examples 1-7 and Comparative Examples 1 and 2)
Emulsion-type acrylic adhesive: 37.0 parts by weight (parts by weight when converted to solids)
Rosin-based tackifier: 4.5 parts by weight (parts by weight when converted to solids)
Phthalocyanine Blue colorant: 1.5 parts by weight
Cissing preventative agent: 2.5 parts by weight
Water: 53,5 parts by weight

Note that in Working Examples 8-11, only the parts by weight of the needle-shaped or spherical particles was varied as illustrated in FIG. 2, while the other constituent ingredients were kept as the same parts by weight in the formula above.
Here follows a description of the tests performed in order to confirm the meritorious effects.

(Ease of Coating)

At the time of manufacture of the transfer tape, a 25 µm polyethylene terephthalate film (band-shaped ribbon) treated with mold-release agent on both sides was coated with an adhesive film according to the various examples described above using a kiss coater to achieve various coating depths. The appearance of the coated surface was evaluated at that time, using the following scale:
5: Absolutely no problems from an appearance standpoint
4: Nearly no problems from an appearance standpoint.
3: A small amount of cosmetic streaking (but no problems in use).
2: A noticeable amount of cosmetic streaking (but no problems in use),
1: Marked streaking thought to be due to needle-shaped or spherical particles becoming caught on the Meyer bar of the kiss coater occurred, also causing problems in use.

(Ease of Cutting: Test A)

A transfer tool with a width of 8,4 mm was used to transfer 10 em of the adhesive film to high-quality paper (the targeted object) and then the transfer tool was moved in the direction of operation of the transfer tool as is while being lifted at an angle of 30° with respect to the targeted object to cut the adhesive film. This test was performed 10 times on each of the examples, and the number of times stringiness occurred was evaluated, using the following scale:
5: Stringiness did not occur.
4: Stringiness of less than 1 mm occurred 1-2 times.
3: Stringiness of less than 1 mm occurred 3-4 times.
2: Stringiness of 1 mm or more occurred 1-3 times.
1: Stringiness of 1 mm or more occurred 4 or more times.

(Ease of Cutting: Test B)

A transfer tool with a width of 8.4 mm was used to transfer 10 cm of the adhesive film to high-quality paper (the target object) and then the transfer tool was lifted as is at an angle of 90° with respect to the target object to cut the adhesive film. This test was performed 10 times on each of the examples, and the number of times stringiness occurred was evaluated, using the following scale:
5: Stringiness did not occur.
4: Stringiness of less than 1 mm occurred 1-2 times.
3: Stringiness of less than 1 mm occurred 3-4 times.
2: Stringiness of 1 mm or more occurred 1-3 times.
1: Stringiness of 1 mm or more occurred 4 or more times.

(Adhesive Strength)

A transfer tool with a width of 8.4 mm was used to transfer 10 cm of the adhesive film to high-quality paper (the target object) which was then adhered to high-quality paper of the same quality as the targeted object. A 2-kg roller was rolled back and forth twice to adhere the two and after 3 minutes elapsed, the adhered object was peeled off. The state of the adhered surface of the adhered object was evaluated, using the following scale:
5: Entire surface ripped.
4: 70% to less than 100% of the entire adhered surface ripped.
3: 50% to less than 70% of the entire adhered surface ripped.
2: Less than 50% of the entire adhered surface ripped, Or the adhered surface became fuzzy.
1: Unchanged from before adhesion.
FIG. 1 presents a comparison of Working Examples 1-6 wherein Claim 4 is adopted in Claim 1 of the present invention, while varying the value stipulated in Claim 3 against Comparative Examples 1 and 2, while illustrating the results of evaluation (with Test A for ease of cutting) and the correspondence with the Claims, Note that the overall evaluation is indicated by the symbols o ○, o, Δ and × in order from best to worst, where the numbers in parentheses indicate the totals of the scale numbers given above. In addition, on the Claim correspondence rows, o indicates correspondence, Δ indicates correspondence but a value closer to the upper or lower limit than the center of the range, while × indicates no correspondence.
Here follows a description of the results of various Examples in FIG. 1 along with the reasons.
Comparative Example 1 had an overall evaluation of × (11). The reason why is because the particles were spherical in shape, the evaluation of ease of cutting Test A was poor.
Comparative Example 2 had an overall evaluation of × (9). The reason why is because the thickness of coating the adhesive film was made thinner than in Comparative Example 1, so the evaluation of ease of cutting Test A was improved over that of Comparative Example 1, but the evaluation of adhesive strength was worse.
Working Example 1 had an overall evaluation of Δ (12). The reason why is because wollastonite with a Mohs hardness of 4.5 was used for the needle-shaped particles, and the maximum grain size and particle length of the needle-shaped particles (hereinafter called the "particle dimensions") was outside the lower limits, so the evaluation of ease of cutting Test A was low. However, needle-shaped particles were used, so the results were better overall than those of Comparative Examples 1 and 2.
Working Example 2 had an overall evaluation of o (13) so the results were better than those of Working Example 1, The reason why is because, although the Mohs hardness was outside the lower limit, the particle dimensions were the lower limit values within the range, so the evaluation of ease of cutting Test A was improved. In addition, needle-shaped particles were used, so the results were better overall than those of Comparative Examples 1 and 2.
Working Examples 3 and 4 had overall evaluations of o ○ (14) so the results were the best of all of the examples shown in FIG. 1. The reason why is because, although the Mohs hardness was outside the lower limit, the particle dimensions were within the range, so the evaluation of ease of cutting Test A was improved.
Working Example 5 had an overall evaluation of o (13) so the results were slightly worse than those of Working Examples 3 and 4. The reason why is because the particle dimensions were values near the upper limits within the range, so the evaluation of ease of coating was slightly lower in comparison to Working Examples 3 and 4. In addition, needle-shaped particles were used, so the results were better overall than those of Comparative Examples 1 and 2.
Working Example 6 had an overall evaluation of Δ (12) so the results were slightly worse than those of Working Examples 3 and 4. The reason why is because the particle dimensions exceeded the upper limits, so the evaluation of ease of coating was lower in comparison to Working Examples 3 and 4. In addition, needle-shaped particles were used, so the results were better overall than those of Comparative Examples 1 and 2.
An overall summary of the various Examples presented in FIG. 1 was given above, where Working Examples 1-6 which adopted at least Claim 1 of the present invention gave results that were better overall than those of Working Examples 1 and 2 which did not adopt the present invention at all. Moreover, in Working Examples 1-6, it was found that the overall evaluation was increased when the maximum grain size of the needle-shaped particles is 5-30 µm and the length of the particles is 30-500 µm.
FIG. 2 presents a comparison of Working Examples 7-11 wherein Working Example 4 which had the best overall results in FIG. 1 is adopted while varying the value stipulated in Claim 4, and also illustrating the results of evaluation (with Test B for ease of cutting). Accordingly, in Working Examples 8-11 among Working Examples 7-11, the amount of needle-shaped particles was varied to the values of 0.3, 0.5, 1.4 and 1.7 parts by weight, thus varying the content ratio. Note that the overall evaluation is indicated by the symbols o ○, ○, Δ and × in order from best to worst, where the numbers in parentheses indicate the totals of the scale numbers given above. In addition, on the Claim correspondence rows, o indicates correspondence, Δ indicates correspondence but a value closer to the upper or lower limit than the center of the range, while × indicates no correspondence.
Here follows a description of the results of various Examples in FIG. 2 along with the reasons.
Working Example 4 had an overall evaluation of Δ (12). The reason why is because the Mohs hardness was outside the lower limit, so the evaluation of ease of cutting Test B was poor. Note that in the following, the evaluation of relative superiority is indicated based on Working Example 4 in FIG. 2 as the reference, but all exhibited results better than Comparative Examples 1 and 2 shown in FIG. 1.
Working Example 7 had an overall evaluation of o ○ (15) so the results were the best of all of the examples shown in FIG. 1 or FIG 2. The reason why is because the requirement of a Mohs hardness of 6 or greater was satisfied, so the evaluation of ease of cutting Test B was improved in comparison to Working Example 4, and also all of the stipulations of the present invention were satisfied.
Working Example 8 had an overall evaluation of o (13) so the results were worse than those of Working Example 7 but better than those of Working Example 4. The reason why is because the particle content ratio was outside the lower limit, so the evaluation of ease of cutting Test B was low.
Working Example 9 had an overall evaluation of o ○ (14) so the results were slightly worse than those of Working Example 7 but better than those of Working Example 8. The reason why is because the particle content ratio was at the lower limit within the range, so the evaluation of ease of cutting Test B was improved over that of Working Example 8.
Working Example 10 had an overall evaluation of o ○ (14) so the results were slightly worse than those of Working Example 7 but roughly the same as those of Working Example 9. The reason why is because the particle content ratio was at the upper limit within the range, so the evaluation of ease of cutting Test B was improved over that of Working Example 9 but the adhesive strength was lower than that of Working Example 9.
Working Example 11 had an overall evaluation of o (13) so the results were worse than those of Working Example 7 but better than those of Working Example 4. The reason why is because the particle content ratio exceeded the upper limit, so the adhesive strength was low.
An overall summary of the various Examples presented in FIG. 2 was given above, where Working Examples 7-11 which adopted at least Claims 1, 2 and 3 of the present invention gave results that were better overall than those of Working Example 4 which did not adopt Claim 2 in particular. Moreover, in Working Examples 7-11, the ease of cutting was good because needle-shaped particles with a Mohs hardness of 6 or greater were used, and also good results were obtained by making the needle-shaped particle content ratio 1.0-3.0 wt.%, particularly when comparing Working Examples 7, 9 and 10 against Working Examples 8 and 11.

Industrial Usability

As described above, the transfer tape according to the present invention has an adhesive film that contains needle-shaped particles, so it maintains strong adhesive strength but the adhesive film can be reliably cut at a stipulated position without generating stringiness, Moreover, even if the adhesive strength is increased, by adopting needle-shaped particles with a Mohs hardness within a range of 6 or greater, by adopting needle-shaped particles with a maximum grain size of 5-30 µm and a particle length of 30-500 µm, and by adjusting the quantity of needle-shaped particles within the adhesive film composition to 1.0-3.0 wt.%, the aforementioned meritorious effects can be obtained and also they become even more marked.

Claims

Transfer tape consisting of a band-shaped ribbon coated with an adhesive film that is peeled from the band-shaped ribbon and transferred to a targeted object to form an adhesive film, characterized in that said adhesive film contains needle-shaped particles.
Transfer tape according to Claim 1, characterized in that the Mohs hardness of the needle-shaped particles is 6 or greater.
Transfer tape according to Claims 1 or 2, characterized in that the maximum grain size of the needle-shaped particles is 5-30 µm and the particle length is 30-500 µm.
Transfer tape according to any of Claims 1-3, characterized in that the needle-shaped particle content is 1.0-3.0 wt.%.